Yes, the true spirit of a "gift" is to give something with no expectations of anything in return.
But, hell, a "thank you" would be nice. Written, preferrably.
Look, people: the gift-giver spent time, money and energy. The least you can do is say -- verbally and written -- "thank you."
There's an unfortunate trend going around right now -- helped along by the retail paper, wedding industry, and photo-ordering sites, no doubt-- of these stupid "photo thank yous."
I'm sad to say that I've received my unfortunate fair share of these lazy, thoughtless photos posing as thank-yous. These flimsy photos have landed in my mailbox after weddings, christenings, and children's birthday parties. The photo cards are pre-ordered by the clueless parents (or, in one case, bride) before the occasion. Immediately after said party, to which I drove over an hour, purchased a gift with my good money, and spent my time watching you corral your brats (or get married, whatever), the lazy parent or lazy bride then shoves a pre-printed photo card with a photo of guest of honor into an envelope, does not include a personalized note, and sends it off.
Frankly, I'm offended. (see effort, time, driving, money, etc. cited above)
Whenever someone makes the effort to show up for you, and has gone to time and expense to bring you a gift, take 30 seconds, grab some note paper, and write a couple sentences of thanks, then spend 42 cents and mail it, lazy ass.